Measured-service telephone system.



B. I). WILLISl MEASUREI) SERVICE TBLEPHNE SYSIBM.

APPLICATION FILED APR 17` IIj 1I Patented 1v1-m9, 1915.

SSIIEE'I'S VSHHETI $614 LME( ULI? B. B. WILLIS.

MEASURED SERVICE TELEPHQNE www.

APPLICATION YILRU APIL'?. lMS

Patented Mar. 9, 1915` 3 SHEETSSHEET I? B. D. WILLIS.

Mkammb 55mm TELEPHONE SYSTEM.

3 SHEETS- HEET 3 UNITED STATES PATENT OFFICE.

BERNARD D. WILLIS, OF CHICAGO, ILLINOIS, ASSIGNOR TQ AUTOMATIC ELECTRIC COMPANY, 0F CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

MEASURED-SERVICE TELEPHONE SYSTEM.

Specication of Letters Patent.

Patented Mar. 9, 1915.

Application led April 17, 1913. Serial No` 761,800.

To all whom yt may concern Be it known that I, Biermann D. WILLis, a citizen of the United States of America, and resident of Chicago, Cook county, Illi nois, have invented a certain new and use ful Improvement in llleasured-Service Telephone Systenis, of which the following is a specification. f i

My invention relates to improvements 1n semi-automatic telephone systems, and more particularly to systems in which measured service is employed. In such systems it is customary to reverse the current in the calling line either before or at the time the called subscribed answers, in order to render the calling telephone inoperative until the calling subscriber operates the measured sereice device. In semi-automatic systems it is preferable and easier to arrange the apparatus so as to obtain this reversal ot current in the calling line at the time when the operator inserts the' plug of her cord circuit into the jack of the called line, rather than at the time the called subscriber answers. As above pointed out, this reversal of current renders the telephone of the calling subscriber inoperative and thus it is evident that when the apparatus is arranged so as to reverse this curent when the plug is inserted in the jack, the operator cannot converse with the calling subscriber until aiter the called subscriber answers without removing the plug from the jack, so as to rcstore the current in the calling line to its normal direction. This is an objectionable feature, as it oftens happens that it is necessary or desirable for the operator to conixnunicate with the calling subscriber during this interval of time.

It isan object of my invention to provide means whereby, when the operator connects lier talking set with the trunk extending to the calling subscriber, after she has made connection with the called subscriber, the current in the calling line is automaticallyr restored to its normal direction, so as to ren der the calling telephone operative for talking purposes. In this manner the operator is enabled to communicate with the calling subscriber without removing the calling plugfrom the j ack of the called line.

A further special object of my invention is to prevent the operator from restoring the current in the calling line to its normal direction so as to render the telephone opera-- tive at any time after the called subscriber answers. In this manner the operator is prevented from rendering the calling tele-` phone operative for talking purposes after the called subscriber has answered, and thus cannot in any way assist the subscribers in carrying on a conversation without 'having the calling subscriber first operate his measured service device.

These and other objects of my invention will be more readily understood by reference to the accompanying drawings, in which I have illustrated one form of semi-automatic system to which my invention is applied.

ln the drawings Figure 1 represents a diagrammatic layout of a telephone system cmbodying the principles of my invention. Figs. 2 and 3 show a complete connection between an automatic line and a manual line in said system.

The telephone system, as illustrated in Fig. 1, comprises a manual exchange M and an automatic exchange A. In the manual exchange M there is represented a switchboard comprising a plurality of operators` positions M and showing trunk lines H from automatic selectors E terminating at the switchboard in plugs P. At S and S2 there are shown two groups of subscribers substations S, each of which is provided at the central ofiice with an answering jack J in one position and multiple jacks J in the other positions, in the usual manner. Suitable plug cords c are provided for making the desired connection. The automatic exchange A is of a well-known type, comprising subscribers individual or line switches C, first selectors E, second selectors F and connectors I. In the drawings there are represented two thousands of a ten thousand line capacity exchange on a scale of three to ten. The subscribers telephones T are divided into groups T', 2 and T3, etc., usually one hundred telephones in a group; Therefore, with the above-mentioned scale, the three groups T', T2 and T3 represent one p thousand lines, andthe other groups T, T 4and T8 represent another thousand. With each group of subscribers lines there is as- Spaulding hundreds :1 re mulLiplid thmiiglr oui, h@ diiareiii. ihuusiuids. The bunk con: taicts QF the Erst level (if these first selectors fir@ cuimctled to trunk knus leading tu sei:- ond Selectur F sscaed with. the iiuiisund, and the Contacts of the second le-.vel are wmucciled tu trunk lim-.5 lending t0 second sriifutnrs; zismwizited with the second tlmugimd. All thu gewild selectors :immriatmi wiih :i gimen thousand :ire multiplied iugethcr, und die rst. Errol connects@ m trunk Pimm l aiding m cumiiciurg which lrirf.; accesi; ik die limb-1. 0i the r hunch-mii gi-min if that. iliiiiisiim. "Hm second leva] is con leading to commercants Eines; 0f iic second hlm-- 'i ii'iinimg; urrangrxilt of :in M sinmgfr is iii gQnr-.ii wili known und it if. 2.11m@ iii muy ii; @scribe r. furirr. 'Elim trunks ii. which esid fiumi '.i cumin riri if the bunk mi 'iinitnrs lil und trrfiiiinie in nriilsmry ai he muuu-.ii mziicibuzuil wir fired.

:iiitwnmti Referring i0 Fig. there 15 shown the 115ml :mlwrribcr' tiflrphuuu 'if with w gh.

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polarized efcrmmigmrl.. thc rails ll and 13 d6 and the side switch wipers 47,. 48, 49 and.

50. YThe switch shaft (not shown) and the` 'line and privateinipers are the direct means of connection between this switch and the trunk H (Fig. 8).

The equipment of the trunk comprises a line relay 54, battery reversing relay 55, two slow acting relays 58 and 57, two quick acting relays and t# and two visual signals GO and G1. Battery current is supplied to the called subscriber through the coil 62 und the relay 63. There is also a ringing relay 611 and ringing cut-od relay (55. At R there is shown a ringing cin-rent generator and at V an operators talking set is shown. For the purpose of indicating when the called subscriber answers after the operator has plugged in, there is provided a visual signal 112. The usual operatofs listening key .K has a pair of extra springs (i9 and 70 for the purpose of making the calling subscribers telephone operativo for talking purposes should the operator wish to speak to him after she has inserted the plug .P into the jack J' to call the called subscriber. The talking circuit through the trunk l'l includes the condensers 71, 72, 73 and 71. Further details ot this trunk equipment will be eX- plained hereinafter in connection with the description oi' the operation of thesysteni.

,At S there is shown an ordinary common l'iattery manual telephone the line conductors of which terminate in the central oilice in the answering jack J and thc multiple jacks J". The line is also provided with the usual line and cutoti relays 36 and (S7 and the si ral lamp (38.

gH'aving given a general description of the apparatus, l will now explain how an automatic subscriber at the substation` T may obtain connection with the Inanual substation S, and will also describe the manner in which the operator is able to render the calli-ug subscribers telephone operative or inoperative at will after she has connected the two lines and before the called subd scriber answers. order to gain connection with the trunk H and to signal the marinai operator the automatic subscriber has to call the digit O. Upon the receiver 4 being lifted from the switch hook, Athe spring 7G breaks away from the spring 75 and makes Contact with the spring 77 to out off the ringer circuit and to bridge the talking circuit across the line, thereby closing a circuit from ground We will assume' that in G17 through the springs 77I and 78, line 2, springs 76 and 77, .primaiy winding of the induction coil, transmitter 5, impulse springs 8 and 9, coilsJl and 12, line 8, springs 78 and 79 and through the winding 23 of the switch C to the battery lead 100. At this time the Acurrentowing through the coils 11 and 12 is in the direction to attract the armatureto the coil 11 to carry the arm 80 behind the lug 81 on the arm 82. The winding 23, .upon energizing, closes the circuit of the pull-down Winding 21, which causes the plunger arm 17 to be attracted to thrust the plunger into the bank .terminals and thus extend the line connection through the springsQ and 27 and 26 and 28 to the sclector E, This circuit extends from ground G through the springs 77a and 83, through the windings 21 and 21 in series and contact 150 to the battery lead 100. The Winding 21, upon energizing, attracts tho cutoff armature 19, in addition to the plunger arm 17. The armature 19 operates to press the springs 78 and 84 together and to separate Vthe springs 78 and 79 and 78 and 77a. The separation of the above-inentioned springs disconnects the Winding 23 wld ground G `from `the line conductors. The armature does not fall back immediatly however,J due to the fact that the Wind ing 24 is energized in series with the pull down Winding 2l. 17 is operated it not only forces the plunger into the bank terminals to extend the connection, but closes the contact of the springs i fore this happens, however, the circuit of i the holding coil 22 is closed in the following manner: When the springs 25 and 26 make contact with the springs 27 and 28, the circuit of the line rela i() in the selector E is closed by reason of t 1e closed bridge at the subscribers telephone. Upon the relay energizing, a circuit is closed for the slow acting relay L15 from ground (ils, contact of springs 181 and 182 and through said relay to the battery lead 100. This relay energizes and brings together the springs 188 and 189 and 190 and 191, which latter closeJ the circuit of the winding :22 from ground G2. The energization ol this winding maintains the plunger arm 17 in an operated position after the circuit of the winding Q1 has been broken. Vhen the springs El and 32 are forced together by the plunger, the stz'irting relay 88 of the master Snitch l) is energized over the circuit extending from ground G21 through said springs and through the relay 88 by way of the wiper 8S) and common segment 38. Upon the relay 88 energizing, the circuit of the lock niagnet 87 is closed, which magnet in turn en- When the plunger arm 'ill :nllu ll'llill: i;

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tion of this relay, the armatures 102 and 113 are attracted, the former completing the circuit already prepared from ground G10 to the contact of springs 70-and 69, 102 and 114, relay 184, springs 109 and 110 and the relay 59 to battery The line lamp 61 is extinguished upon the plug being inserted into the jack J', for its circuit is opened by the armature 102 of the relay 111 breaking away from the spring 103. The armature 113, upon being attracted, breaks contact with the spring 117 and makes contact with the spring 118. The contact with the spring 118 does not accomplish anything at this time, as the line circuit is open at the telephone S. The breaking of the contact with the spring 117 disconnects from the line the tertiary test winding 119 on the induction coil in the operators talking set V. The spring 115 is also attracted when the relay 111 is energized, thereby closing a circuit from ground x13 through the contact of springs 115 and 116, contact of springs 108 and 120, througli the relay 64 and the interrupter 105 to battery B. This circuit being intermittently opened and closed causes the relay 64 to alternately disconnect the calling line from the called line and to bridge the ringer generator R across the called line to send out alternating current to ring the bell at the substation S. It will be remembered that upon the operator inserting the plug P into the jack Jv a circuit was closed through the relays 1S4lgand 59 at the contact of springs 102 and 103: This circuit causes the armature of the relay 184 to be attracted to prepare a circiiit through the supervisory lamp 60. The relay 59, upon energizing, presses together the springs 122 and 123, thereby closing a circuit from ground G" through the contact of said springs and through battery reversing relay to battery B. The battery reversing relay energizes to take the springs 94 and 97 out ot engagement with the springs 93 and 98 and place them in contact with the springs 124 and 125. This operation changes the direction of the flow of current through the calling subscribers telephone and coin-co lccting device L by interclianging the connection between the trunk conductors 95 and 96 and the terminals of the battery through the windings of the relay lThe change of direction of current throughthe coils 11 and 12 (Fig. 2) attracts the armature 126 to the coil 12, thereby` applying pressure against the lug 81 on the arm 82 to carry said arm into the rslot of the coin chute and to close the contactiof springs 13, l-l and 1T), ewhich, as has been stated previously, short-circuits the trans` mitter 5 and shunts the receiver 4, rendering thetelephone 'Il inoperative. This condition is maintained until the calling party f lrops a coin into the chute, the weight of which coin will knock the lug 81 out of engagement with the arm 80 and restore the transmitter and receiver to their normal condition.

It is sometimes necessary or desirable for the operator to communicate with the calling subscriber after shc has inserted the plug into the jack of the called line and while the called subscribers receiver is on its switch hook. Since the calling telephone is rendered inoperative for talking when the plug P is inserted into the jack J'. and remains so as long as the called subscribers receiver remains on its switch hook, it is evident that unless the operator is provided with some other means for rendering the calling telephone operative, she cannot converse with the calling subscriber during this time without removing the plug from the jack. It is the object of the extra springs 69 and 70 of the key K to enable the operator to render the calling telephone operative by the simple act of connecting the talking set V into circuit. Upon the operation of the key K to connect the talking set into circuit, the separation of the springs 70 and 69 opens the circuit of the Irelays 184 'and 59. The relay 59, upon denergizing, opens the circuit of the relay 55, which in turn de'cnergizes and restores the current in the calling line to its normal direction, whereupon the armature of the coin-collecting device is again attracted toward the coil 11, whereby the springs 13, 14 and 15 are opened. When the operator restores her key K, the current in the calling line is again reversed and the substation T is returned to its inoperative condition.

Upon the called subscriber removin7 his receiver to answer the call, a bridge is c osed across the line at the subscribers station including the spring 156 and the switch hook 157. This closes a circuit from ground G through the impedance coil 62, contacts of the springs 128 and 129 (when the ringer relay is denergized), contact of springs 11B and 113, tip of the plug P and jack J', through the switch hook contact at the telephone, ring-ot' the plug P, contact of springs 130 and 131 and through the relay 63 to battery B. Upon the relay 63 energizing, the circuit of the ringing cut-off relay is closed, which circuit can be traced from ground G to the contact 132 and through said ringing eut-ofil relay to battery B. Upon the relay 65 energizing, the armature 108 breaks contact with the spring 120 and makes contact with the spring 107, the breaking of the contact between thearmature 108 and the spring 120 being the means ot' permanently denergizing the ringing relay 64 to disconnect the 4 ma 'u mn f thi-1 ruling :1i-winni? mi Hiv w-Inf, .W anni iis crrxui is rr-roken at the springs lmi Hf when the Ew'etch Shft comes to re t. L '1, 'whmgvr umn 1'? of the Swch C is reloaw by the denergization of the Winding .m1113112 nm? n?, ith@ over this trunk include one ofV the talking conductors.

While l halve illustrated and described one particular embodiment of my invention, it will, oit course, be understood that many changes and modifications can be made without departing 'from the spirit and scope of my invention.

What l claim as my invention is l. ln a telephone system, a plurality of subscribers lines, means including an operators connecting link for establishing a. connection between two of said lines, an o erator"s talking set associated with said link, means for rendering the calling telephone inoperative upon completion of the connection with the called line, and means for rendering the calling telephone again operative without breaking the connection be tween said operators link and the called line when said operators set is connected with the connecting link before the called subscriber answers.

Q. In a telephone system, a plurality of subscribers lines, means including an opel-` ators connecting link for establishing a connection between two of said lines, an operators talking set associated with said link, means for rendering the calling telephone inoperative upon completion of the connection with the called line, means for rendering the calling telephone again operative without breaking the connection between Said operators link and the called line when said operators set is connected with the connecting link before the called subscriber answers, and means for preventing the operator from rendering the calling telephone operative after the called subscriber answers.

3. In a telephone system, a plurality of subscribers lines, means including an operators connecting link for establishing a con nection between two of said lines, an operators talking set associated with said link, means for rendering the callingr telephone inoperative upon completion of the connec tion with the called line, means for render` ing the calling telephone operative without breaking the connection between said operatcrs link and the called line when said operators set is connected .with the connecting link before the called subscriber answers,

.and means for rendering the calling telcphone operative upon the response of the called subscriber, and means for preventing the 'o erator from rendering the calling telephone operative after-the called subscriber answers.`

4f. In a telephone system', a calling and a called subscriberls line, an operators trunk circuit adapted to be connectecLwith the called line, means including automatic switches for extending a connection from the calling line to said trunk circuit` an operator-s talking set associated with said trunk circuit and adapted to be connected thereto, means for rendering the calling tele hone inoperative when connection is completcd with the called line. and means for rendering said telephone operative when said operator connects the talking set with said trunk circuit.

5. In a telephone system, a calling and a called subscribers line. an operators trunk circuit adapted to be connected with the called line, means including automatic switches for extending a connection from the callingr line to said trunk circuit, an op crators talking set associated with said trunk circuit and adapted to be coniuuizted thereto, means for rendering the. calling telephone inoperative when connection is completed with the called line, and means for rendering said telephone operative when said operator connects the talking set with said trunk circuit without breaking the corn nection with the called line and before the called subscriber answers.

6. In a telephone system, a calling and a called subscribers line, an operators trunk circuit adapted to be connected with the called line, means including :n.itomatic switches ,for extending a conm tion from the calling' line to said trunk circuit, an operators talking set associated with said trunk circuit and adapted to be connected thereto, means for rendering the calling tele-f phone inoperative when connection is completed with the called line, means 'for ren.- dering said telephone operative when said operator connects the talking set with said trunk circuit without breaking the connection with the called line and before the called subscriber answers, and means for preventing the operator rendering the calling telephone operative after the called subscriber answers.

7. In a telephone system, a plurality of subscribers7 lines, means including an operators connecting link for establishing s connection between two ot said lines, an operators talking set associated with said link, means for reversing the current in the celling line to thereby` render the calling tela phone inoperative upon completion of con` nection with the called line, and means for again reversing the current in the calling line to render the calling telephone opera tive without breaking the connection between said operators link and the called line when said operator`s set is connected with the connecting link before the called subscriber answers.

S. In a telephone system. a plurality of subscribers` lines` menus including an operators connecting link for establishing a ron-- noi-tion between two of said li nos. :in opera-- tors talking set associated with said link. means for reversing the current in the calling'- line to thereby render rho calling telelimi 16.1In a telephone system, a lurality of subscribers lines, means inclu ing an operators link circuit for establishing a connection between two of said lines, an o perators talkingset, a listening key for conneeting said set with said link circuit, a bridge across the conductors of the talking circuit, said bridge including a line relay and a battery connected to said bridge for supplying' current to the calling line, a current-reversing relay, means for energizing said relay when connection is made with the called line to reverse the battery connections in said bridge to thereby reverse the current in the calling line, means controlled by said reversal of current 'for rendering the calling telephone inoperative, means controlled by the o eration of said listening key before the ca led subscriber has answered for denergizing said current-reversing relay to thereby render said calling telephone operative, and means for preventing the operation of said listening key from rendering said calling telephone operative after `the `called subscriber has answered.

17. In a telephone system, a plurality of subscribers lines, means including an operators link circuit for establishing a connection between tWo of said lines, an operators talking set,`a listening key for connecting said set with said link circuit, a

.current-reversing relay for reversing the current in the calling line, means controlled by said reversal of current for rendering the calling telephone inoperative, and a circuit for controlling said current-reversing relay, 'said circuit including normally open contacts adapted to be closed when connection is made with the called line and normally closed contacts controlled by said listening key.

18. In a telephone system, a plurality of subscribers lines, means including a trunk circuit terminating in an operators link circuit for establishing a connection between two of said lines, an operators talking set associated with said link circuit, a listening key for connecting said set with said link circuit, a current-reversing relay, and means for energizing said relay, said means including a circuit passing over one side of the trunk circuit and having normally open contacts adapted to be closed when connection is made with the called line and normally closed contacts controlled by said operators key.

19. In a telephone system, a plurality of subscribers lines, automatic means and an operators connecting link for establishing a connection between two of said lines, an operators talking set associated with said link, automatic means for rendering the calling telephone inoperative upon completion of the connection with the called line, and automatic means for rendering the calling telephone again operative without breaking the connection between said o erators link and the called line when sai operators set is connected with the connecting link before the called subscriber answers.

20. In a telephone system, a pluralit of subscribers lines, automatic means an an operators connecting link for establishing a connection between two of said lines, an operators talking set associated with said link, automatic means for rendering the calling telephone inoperative upon completion of the connection with the called line, automatic means for rendering the calling telephone again operative without breaking the connection between said operators link and the called line when said operatorls set is connected with the connecting link before the called subscriber answers, and automatic means for preventing the operator from rendering the calling telephone operative after the called subscriber answers.

21. In a telephone system, a plurality of subscribers lines, automatic means and an operators connecting link for establishing a connection between two of said lines, an operators talking set associated with said link, automatic means for rendering the calling telephone inoperative upon completion of the connection with the called line, electrical controlled means for rendering the calling telephone again operative without breakin the connection between said operators lin( and the called line when said operators set is connected with the connecting link before the called subscribed answers, automatic means for rendering the calling telephone operative upon the response of the called subscriber, and automatic means for preventing the operator from rendering the calling telephone operative after the called subscriber answers.

22. In a telephone system, a calling and a called subscribers line, an operators trunk circuit adapted to be connected with the called line, circuit means including automatic switches for extending a connection from the calling line to said trunk circuit, an operators talking set associated with said trunk circuit and adapted to be connected thereto, automatic means for rendering;F the calling telephone inoperative when ennnectinn is eonipleteii. with the Called line, and antonmtie means for rendering said telephone operative when said operator connects the talking set with said trunk circuit.

In :1. telephone system. a, calling and a Called subset iliers line, in operators trunk eilunit adapted to be eonnectefl with the ealloel line, circuit means including anto- Inatie switches t'or extending a` eonnertion from the CallingF line te saiil trunk circuit, an oneratnis talking set associated with saifl trunk circuit and adapted to be Connected thereto, automaticy means for rendering the calling telephone ininierative when connectinn is eoinnieteil with the called line, and antoinatie means for rendering sniil telephone open ve. when said operator connects the talking set with said trunk eireut without breaking the Connection with the called line and before the called subscriber answers.

Dit. In a telephone system, a calling and a Callefl subsei'iliei"s line, an oiieratofs trunk eiienit adapted to be connected with the eallefl line` automatic means ineindingr automatic sn'itehes tnx' extending' a connection from the Calling line tn said trunk ci;-` enit. an operators talkingl set .-issoeiatefl with said trunk eii'euit and adapted to he :fonnleteil rherettn automatic means tor rendering the ealling;r telephone inoperative when Connection is completed with the ealled inni, automatic nleans for rendering saill telephone ngiei'ative when said operator connects the talking` set with said trunk ein enit without breaking the Connection with the eaileti line anrl beten-e the called sulisir-Film answers, and automatic means for preventing the nperntor rentleiing the callinnr telepl'irine operative allier the eallefl sul)` seriliier answers,

Q5 ln a telephone system` a plurality of snliserihers` lines` eir'enit means inelinlingt`r an i'iiiei'ati'nis Wnneetinnr link for' estalilishing' a ee'iniwetinn between two of sairl lines` an operatofs talking' set assneiateil v. ith said link` alibi-natie means 'oi' reversing the eurient in iiie chilling limI tn thereby i'enrlei the calling nleiinfne inoperative anon completion nt enni'ieetii'in, with the ealleel line. ainl aiitoniatiij: means tni again reversing the current in the nailing line to renale." the nails ing;F teieiihone operative without tweaking the winneetini': lieineen saiil ope|'ato1"s link :unil the ealieil line 'when said nina-ators set is ennneeti-l with the eonneeting link before the eallei'l siilisei'ilier answers.

Yin a teleplmne system, a plurality ot' snlir-t "lans" linrs tiri-nit means including an nia-retries :rnnniiting link for estalilisllingA :i militari-tien liet-veen two of sairl lines. `Iin egierat'nfs talkingl set associated with said link. antoiziatie means fin' i'eieising: the eur-- rent in the calling line t0 thereby render the` Calling telephone inoperative u ion e-'nnpletion of connection with the eal eil line, automatic means fin' again reversing the euri'ent in the calling line to render the ealling telephone'operative without breaking the eonneeion between saifl opet'nfnr`s link and the called line when said opefatfn-s set is eonnected with the connectinglink before the called subscriber answers` and antmnatic means for preventing the operator from 1eieising the current in the called line to renfler the calling telephone npei'ative .after the called subscriber answers.

Q7. In a telephone system, a Calling and a called snliseribers line, an operators trunk Circuit adapted to he Connected with the Called line, means including automatic Switches for extending a connection from the calling line to said trunk Circuit, an npeiators talking set associated with said trunk circuit and adapted to lie eonineeteil thereto,y automatic means for reversing' the current in the calling line to ren der the calls ing telephone inoperative lien emmeetinn is completed with the, called line` and auto matie means for airain reversing the entrent in the calling line to render the telephone operative when the operator connects the talkingr set with said trunk circuit.

29.111 a telephone system` :t Callingr and a ealled subscribers line, an operators trunk eiieuit adapted to be eonneeted with the ealleit line, circuit means including,r antoiatie switehes for extending a eonneetion 'from the (fallingr line to said trunk eii'enit, an oiiei'ators talkiingy set associated with. said trunk circuit nml adapted to he eon neeteil thereto, automatic means for reversing' the enrrent in the callingr line tn render the, milling' telephone inoiieratii'e when ennneetion is Completed with the Called line, and automatic means for again reversing the, euri-ent 1n the calling,1r line to ienclei.' the telephone operative when the onei'ator eonneets the talking set with said trunk eir-A euit without breaking the eonneetion with the called line alnl before the Calleri sul serilier answers.

2i). in :l telephone sistem` a Calling :intl a ealleil sl1lisr-l'il)et"s line7 an operatofs trank eiiellit adapted to he eonneeteijl with the ealled line, eirmiit meansI ineluilinuf,r anto-` rnatie switehes for erm-rndini;r a ennneetion from the eallinnr line to said, trunk eirenin an operatoi"s talking set assoeiatefl with said trunk circuit :mil adapted to he eon netzteil thereto` automatic means for reversing the eurrent in the calling` line to Vernier the ealling telephone inoperative when ennneetion is f'oinpleteel with the ('alleil line, autoniatie means for again reversing the current, in the calling line to render the telephone operative when the operator consubscribers lines,

nects the talking set with said'trunk circuit without breaking the connection with the called line and before the called subscriber answers, and automatic means for preventving the operator from reversing the currentl in the called line to render the calling telephone operative after the called subscriber answers.

30. In a telephone system, a plurality of circuit means including circuit for establishing a connection between two of said lines, an operators talking set, a listening key for connecting said set with said link circuit, a current-reversing lrelay, automatic means for energizing said relay when connection is made with the called line to reverse the current in the callingline, and circuit means controlled by the operation of said listening key for denergizing said current-reversing relay, so that the current flows over the calling line in the normal direction.

3l. In a telephone system, a plurality of subscribers lines, circuit means including an operators link an operators link circuit for establishing a of said lines, an `o|`3 connection between two erators talking set, a listening key 4for connecting said set with said link circuit, a current-reversing relay, automatic lmeans Vfor energizing said relay to reverse the current in the calling line when connection is completed with the called line, automatic means operated by said reversal of current for rendering the calling telephone inoperative', and means controlled by the operation of said listening key for denergizing said current-reversing relay to thereby render said calling telephone operative, whereby the operator can communicate with the calling subscriber.

v32. In a telephone system, a plurality of subscribers lines, circuit means including an operators link circuit for establishing a connection between two of said lines, an.operators talking set1 a listening key for connecting said set with said link circuit, a. current-reversing relay, automatic means for energizing said relay to reverse the current in the calling line when connection is completed with the called line, automatic'means operated by said reversal of current for rendering the calling telephone inoperative, automatic means controlled by the operation of said listening key before the `called sub-` 4necting said set with Y. called line connection between two of said lines,an operators talking set, a listening key for consaid link circuit, a bridge across -tlie conductors of the talking circuit, said bridge including a line relay and a battery connected to said bridge for supplying current to the calling line, a current-reversing relay, automatic means for energizing said relay when connectionV is made with the called line to reversethe bat-r tery connections in said bridgeto thereby reverse the current in the calling line, means controlled by said reversal ofcurrent for rendering the calling telephone inoperative, and means controlled by the operation of said listening key for denergizing current-reversing relay, whereby the current flows over the calling line in-the normal direction. i

34. In a telephone system, a plurality o f subscribers lines, means including ators link circuitfor establishing a connection between two of said lines, an operators talking set, a listening key for connecting said set with said link circuit, a bridge across the conductors of the talking circuit, said bridge including a line relay and a battery connected to said bridge for suppl Ying current to the calling line, a current-revers; ing relay, automatic means for energizing said relayv when connection is made with the to reverse the battery connections in saidbridge to thereby reverse the current in the calling line, automatic means con-l trolled by said reversal of current for ren# dering the calling tele hone inoperativ circuit means -controlled y the operation o said listening key before the called sub# scriber has answered for'dener 'zing said current-reversing 'relay to there y render said calling telephone operative, and'automatic means for preventing-the operation of said listening key from rendering said calling telephone operative after the called subscriber has answered.

`35. In a telephone system, a plurality of subscribers lines, circuit means including an operatorsV link circuit for establishing a connection bet-Ween two of said lines, an operators talking Set, e listening key for connecting said setl with said link circuit, a current-reversin relay for reversing the current in the calling line, automatic means controlled by said reversal of current for rendering the calling telephone inoperative, and a circuit for control ing said currentreversing relay, said circuit including normally open contacts adaptedto be closed whenonnection is made with the called line and normally closed 'cbntacts controlled by said listening key.

36. In a telephone system, u plura'lty of subscribers lines, ,circuit means including a trunkcircuit terminating in an operators anY oper? link circuit for establishing a connection between two of said lines, an operators talk ing set associated with Suid link circuit, n listening key for connecting said set with said link circuit, a current reversing relay, and circuit means for energizing said relay, said means including a circuit passing over one. side of the trunk circuit and having normally open contacts adapted to be closed when connection is made with the called line and normally closed contacts controlled by said operators key.

Signed by me 'at Chicago, Cook county, Illinois, this 11th day of April, 1913.

, BERNARD D. WILLIS. Witnesses:

ALBERT ANDERSEN, ARTHUR J. RAY.

Corrections in Letters Patent No. 1,130,784-

i It is hereby certied that in Letters Patent No. 1,130, 784, granted March 9, 1915, i upon the application of Bernard D. Willis` of Chicago, Illinois, for an improvement in MeasuredServce Telephone @ye-tems, an error appears in the printed specification requiring correcbion es follows: Page (j, line 80, and page 9, line 113, for the Word subscribed read subscriber; and that the said Letters Patent should be read 1 with this correction` therein that, the same may conform to the record of the case l in the Patent Of'ice.

Signed and sealed this 4th day of May, A. D., 1915.

[SEAL] R. F. VVHITEHEAD,

Acting Commissioner of Patmta. 

